ISLAMABAD (Reuters) - Pakistani poet and activist Salman Haider who went missing from the capital Islamabad earlier this month, just days after four other human rights campaigners disappeared, has been found, his family said on Saturday.

The five missing liberal activists, some of whom have posted blogs criticising the political influence of the military and speaking up for the rights of religious minorities, had each gone missing separately since Jan. 4.

"Salman is fine, he is safe and we are happy he is back with us," Haider's brother Zeeshan Haider told Reuters, declining to elaborate on where he was.

Zeeshan said he had not met his brother yet but had spoken to him on the phone while several other family members had personally met him.

"Salman has a bad skin condition so I have been really worried about that but when I spoke to him he assured me that he was in good health," Zeeshan said. "And whoever in the family has met him says that he looks healthy and happy."

Police sources earlier told Geo News channel that Haider, who disappeared on Jan. 6, was found late on Friday night but did not give further details on how he was found.

There was no word on the whereabouts of the four other missing activists.

Neither the family nor authorities quoted in local media gave details of where Haider had been and what had happened to him.

It is also not known how the five activists went missing, but some rights groups and newspapers have asked whether state or military agencies were in any way involved.

The Interior Ministry has repeatedly said it was doing all it could to recover the missing men. The military and other state agencies have declined to officially comment.

Shortly after the activists' disappearances, blasphemy allegations against them appeared on social media and in a complaint to police.

Friends, family and supporters of all five men deny they have blasphemed, and have denounced the campaign to press that charge, which could endanger their lives were they to reappear.

In Pakistan, conviction under the blasphemy laws can carry a mandatory death sentence.

Haider has written columns for a popular English-language newspaper and taught at the Fatima Jinnah Women's University in the city of Rawalpindi, some 15km from capital Islamabad.

Last year, Haider wrote a poem about human rights abuses in Pakistan's restive Baluchistan province, including a line about his friends' friends disappearing. He queried whether his friends, or even he himself, will be next to suffer such a fate.

Two of the missing activists, Waqas Goraya and Aasim Saeed, live in the Netherlands and Singapore. Their relatives said they were taken on Jan. 4 while visiting Pakistan. The fourth activist, Ahmed Raza Naseer, suffers from polio.

A fifth Pakistani social activist, Samar Abbas, went missing from the capital Islamabad on Jan. 11.